[openib-general] librdmacm/ucma

[Michael S. Tsirkin]

Sean, I'd like to see some things with librdmacm/ucma code improved:

- dependency on libsysfs
  I propose we don't get into this again. I know we have it in ibverbs
  but let's avoid for new code.

- negative error codes
  I think this is kernel practice, in userspace we
  either set errno and return -1, or simply return
  positive error code: otherwise utilities like strerror
  do not work

- abi versioning
  The RDMA_USER_CM_MAX_ABI_VERSION idea is broken - it makes it so that you are
  required to upgrade userspace to run on older kernels.
  Bailing out in userspace if the kernel is too new is not good - please
  remove this test.

  We need to be able to run old userspace on old kernels too - that's
  how the rest of the kernel understands backward compatibility.

-- 
MST